The present invention relates to a driving device using a general-purpose motor with a velocity controlling circuit attached.
In an image forming device having a plurality of photoconductors (hereinafter, also referred to as photoreceptors) whereon electrostatic latent images are formed and a transfer body whereon electrostatic latent images are transferred, the photoconductors and transfer body are preferably driven at a fixed velocity. When a difference (different velocities) is generated in velocity between the photoconductors and the transfer body, images cannot be transferred from the plurality of photoconductors at a fixed position, thus the color mismatching occurs in the full color image.
As a factor for different velocities, it may be considered that a driving roller for driving the photoconductors and transfer body is driven by a motor via a gear driving transmission mechanism such as a plurality of gears, so that variation factors such as the backlash and eccentricity of the plurality of gears are not transmitted to the control system of the motor.
Therefore, Patent Document 1 discloses an image forming device, as a driving roller for driving the photoconductors and transfer body without using drive transmission gears causing different velocities, having a structure of including the motor body inside the roller and a motor of an outer roller (roller-in motor) for driving the housing.
[Patent Document 1]
Tokkaihei 6-271131
According to the invention described in Patent Document 1, however, it is necessary to form a motor and a driving device only for driving the photoconductors and transfer body, thus an increase in cost is caused.
Further, as factors for different velocities, in addition to the backlash and eccentricity of the plurality of gears, the electrical effect when the photoconductors and transfer body are charged and the effects of the contact resistance when the photoconductors make contact with the transfer body, expansion and contraction variations of an elastic body such as a belt as a member used in the transfer body and photoconductors, the distortion and eccentricity of a metallic member used for a drum, and the rushing resistance of paper when it is conveyed to the transfer body as a recording material may be cited.
Therefore, in addition to velocity control by the motor itself, velocity variations caused by variation factors such as the gears driven by the motor, photoconductors, and transfer body must be reduced.